This is a wonderful source of metal references and explanations of the material and how they react.

I chose to use alloy metal, with black & white plastics.

one of the difficulties was this object it all made of metals so i have to make it look more interesting than it is,

one of my mentor selection was to add more heat & burning marks like rainbows when welding.

another experiment i did was to use Displace Map only in areas that i want, so i discover that when i'm using transparent as the background i'm not effecting the geometry that i don't want to be effected, while i tried to keep the geo in the same structure with Vray Displacement there was a slight offset to the whole object.